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SABCS 2023: Impact of Bilateral Mastectomy on Survival Among Patients With BRCA1-Mutated Breast Cancer

By: Chris Schimpf, BS
Posted: Wednesday, January 3, 2024

Undergoing bilateral mastectomy as an initial treatment may not decrease the risk of death among patients with breast cancer and a BRCA1 mutation, according to research presented at the 2023 San Antonio Breast Cancer Symposium (SABCS; Abstract GS02-04). In their large multicenter study, Kelly Metcalfe, RN, PhD, of the Women’s College Research Institute in Toronto, and colleagues reported that although women with a BRCA1 mutation who develop contralateral breast cancer have double the risk of mortality of those who do not develop contralateral breast cancer, they observed only a small, nonsignificant reduction in mortality among patients who had preventive bilateral mastectomy. Noting that longer follow-up is required, the researchers recommended counseling patients with a BRCA1 mutation on the risks of contralateral breast cancer and making surgical decisions accordingly.

A total of 2,482 women with breast cancer and a BRCA1 mutation were included in the study, drawn from 26 centers in 11 countries. Participants were followed from the date of breast cancer diagnosis to either the date of last follow-up or the date of death. The mean patient age at the time of breast cancer diagnosis was 43.1.

The investigators reported that the 15-year rate of breast cancer–specific survival for the entire cohort was 82.9%, compared with 78.7% for patients who had a unilateral mastectomy, 86.2% for those who had a lumpectomy, and 88.7% for those who had bilateral mastectomies. Among patients who underwent initial unilateral surgery, 529 had a subsequent contralateral or bilateral preventive mastectomy. After adjusting for the patient’s age at diagnosis, tumor size, nodal status, whether or not chemotherapy was received, and time-dependent preventive mastectomy, the investigators reported a hazard ratio of 0.78 for breast cancer mortality with bilateral surgery vs unilateral surgery (95% confidence interval = 0.55–1.13; P = .19).

Disclosure: Dr. Metcalfe has received consulting fees from AstraZeneca, Roche, Novartis, Biocad, R-Pharm, Eisai, Eli Lilly, Pfizer, MSD, and BMS. The other study authors reported no conflicts of interest.

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